Moon power

The site, at La Rance, was chosen because the difference between high and low tide there is one of the biggest in the world.

The tidal power station generates enough electricity for 250,000 homes. So it could power a large city.

This sounds like a lot, but, worldwide, tidal power supplies less than 1 per cent of the world's electricity.

Tidal power is good for lots of reasons. The tides are caused by the Moon and the Sun moving around the Earth and so in many places the tides happen twice a day without fail.

This means that it is a more reliable way of generating electricity than using wind or sunshine.

And generating electricity this way doesn't produce any greenhouse gases that cause climate change.

Sounds too good to be true? Well, there are some problems.

Tidal power stations can have an effect on water quality. They can also disturb fish or birds that use the water.

The tidal power station at La Rance has very little impact on the environment, but this may not be the case for all tidal power stations. Would you be prepared to damage the local environment in order to have a reliable power station that doesn't produce greenhouse gases?